In a little more detail...

Add-ons I've created

http://en.wikipedia.org/wiki/Text-to-voice. TTS gives Firefox the power of speech. Select text, click the button on the bottom right of Firefox window and this add-on speaks the selected text for you. Isn't it brilliant? Audio is downloadable.

Link Checker / Link Finder helps you finding your links on other websites. Especially useful for SEO guys. You just need to tell your website name to this addon and it'll highlight your links on all other websites. NoFollow links are marked Red.

Now you don't have to rely on a website's search any more, rather use this website-specific Google search. Bonus is Similar site search. Just on a click, it gets you the list of websites similar to the one opened in active tab.